a)A=2/5+ -4/3+ (-1/2)
b)B=1/3 - [(-5/4)-(1/4+3/80
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DH
7 tháng 7 2017
a, \(3.\left(\dfrac{5}{3}x-7\right)-2\left(1,5x+6\right)-\left(5-x\right)\left(x+4\right)=80+x^2\)
\(\Rightarrow5x-21-3x-12-\left(5x+20-x^2-4x\right)-x^2=80\)
\(\Rightarrow5x-21-3x-12-5x-20+x^2+4x-x^2=80\)
\(\Rightarrow5x-3x-5x+4x+x^2-x^2=80+21+12+20\)
\(\Rightarrow x=133\)
Câu b tương tự! Cứ tách ra!
Q
7 tháng 7 2017
a) \(3\left(\dfrac{5}{3}x-7\right)-2\left(1,5x+6\right)-\left(5-x\right)\left(x+4\right)=80+x^2\) (1)
\(\Leftrightarrow\left(5x-21\right)-\left(3x+12\right)-\left(5x+20-x^2-4x\right)=80+x^2\)
\(\Leftrightarrow5x-21-3x-12-5x-20+x^2+4x=80+x^2\)
\(\Leftrightarrow x-53+x^2=80+x^2\)
\(\Leftrightarrow x+x^2-x^2=80+53\)
\(\Leftrightarrow x=133\)
Vậy tập nghiệm phương trình (1) là \(S=\left\{133\right\}\)
b) chưa rõ đề.
NT
Nguyễn Thị Thương Hoài
Giáo viên
VIP
21 tháng 9
Bài 1:
a; (\(\dfrac{1}{4}\)\(x\) - \(\dfrac{1}{8}\)) x \(\dfrac{3}{4}\) = \(\dfrac{1}{4}\)
\(\dfrac{1}{4}x\) - \(\dfrac{1}{8}\) = \(\dfrac{1}{4}\) : \(\dfrac{3}{4}\)
\(\dfrac{1}{4}\)\(x\) - \(\dfrac{1}{8}\) = \(\dfrac{1}{4}\) x \(\dfrac{4}{3}\)
\(\dfrac{1}{4}x\) - \(\dfrac{1}{8}\) = \(\dfrac{1}{3}\)
\(\dfrac{1}{4}x\) = \(\dfrac{1}{3}\) + \(\dfrac{1}{8}\)
\(\dfrac{1}{4}\) \(x\)= \(\dfrac{8}{24}\) + \(\dfrac{11}{24}\)
\(\dfrac{1}{4}x=\dfrac{11}{24}\)
\(x=\dfrac{11}{24}:\dfrac{1}{4}\)
\(x=\dfrac{11}{24}\times4\)
\(x=\dfrac{11}{6}\)
NT
Nguyễn Thị Thương Hoài
Giáo viên
VIP
21 tháng 9
b; \(\dfrac{12}{5}:x\) = \(\dfrac{14}{3}\) x \(\dfrac{4}{7}\)
\(\dfrac{12}{5}\) : \(x\) = \(\dfrac{8}{3}\)
\(x\) = \(\dfrac{12}{5}\) : \(\dfrac{8}{3}\)
\(x\) = \(\dfrac{12}{5}\) x \(\dfrac{3}{8}\)
\(x\) = \(\dfrac{9}{10}\)
20 tháng 5 2022
a: =>5x-21-3x-12+(x-5)(x+4)=80+x2
\(\Leftrightarrow x^2-x-20+2x-33=x^2+80\)
=>x-53=80
hay x=133
b: \(\Leftrightarrow\left(\dfrac{1}{5}x-\dfrac{2}{3}\right)\cdot\left(\dfrac{4}{3}x^2+1\right)\cdot\dfrac{1}{6}=\dfrac{22}{45}:\dfrac{4}{5}=\dfrac{11}{18}\)
\(\Leftrightarrow\left(\dfrac{1}{5}x-\dfrac{2}{3}\right)\left(\dfrac{4}{3}x^2+1\right)=\dfrac{11}{3}\)
\(\Leftrightarrow\dfrac{4}{15}x^3+\dfrac{1}{5}x-\dfrac{8}{9}x^2-\dfrac{2}{3}-\dfrac{11}{3}=0\)
\(\Leftrightarrow\dfrac{4}{15}x^3-\dfrac{8}{9}x^2+\dfrac{1}{5}x-\dfrac{13}{3}=0\)
\(\Leftrightarrow12x^3-40x^2+9x-195=0\)
hay \(x\in\left\{\dfrac{10+\sqrt{685}}{6};\dfrac{10-\sqrt{685}}{6}\right\}\)
\(A=\frac{2}{5}+\left(-\frac{4}{3}\right)+\left(-\frac{1}{2}\right)\)
\(A=\frac{12}{30}+\left(-\frac{40}{30}\right)+\left(-\frac{15}{30}\right)\)
\(A=-\frac{43}{30}\)
b) \(B=\frac{1}{3}-\left[\left(-\frac{5}{4}\right)-\left(\frac{1}{4}+\frac{3}{80}\right)\right]\)
\(B=\frac{1}{3}-\left[\left(-\frac{5}{4}\right)-\frac{23}{80}\right]\)
\(B=\frac{1}{3}+\frac{123}{80}\)
\(B=\frac{449}{240}\)